Laser processing apparatus, laser processing method, and method for manufacturing semiconductor apparatus

ABSTRACT

A laser processing apparatus and a laser processing method that can effectively prevent a processing time for one semiconductor film from increasing are provided. A laser processing apparatus (1) according to an embodiment includes a laser light source (2) configured to irradiate a semiconductor film (M1) with a laser beam, a film state measuring instrument (5) configured to measure a state of the semiconductor film after the semiconductor film (M1) is irradiated with the laser beam, and a laser light adjusting mechanism configured to adjust a timing at which the semiconductor film (M1) is irradiated with a next laser beam and intensity of the laser beam according to the state of the semiconductor film (M1) measured by the film state measuring instrument (5).

TECHNICAL FIELD

The present disclosure relates to a laser processing apparatus, a laserprocessing method, and a method for manufacturing a semiconductorapparatus.

BACKGROUND ART

A laser processing apparatus that irradiates a semiconductor film suchas an amorphous silicon film formed over a substrate with a laser beamto crystallize or modify the semiconductor film is known. PatentLiterature 1 discloses a technique for measuring a film surface shape bya laser processing apparatus.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent No. 3794482

SUMMARY OF INVENTION Technical Problem

Incidentally, with a laser processing apparatus according to acomparative example developed by the present inventors, the number oftimes of laser beam irradiation per one location over a semiconductorfilm is set to 10 to 20 times. In each time of the laser beamirradiation, the temperature of the part of the semiconductor film whereit is irradiated with the laser beam is raised from a normal temperatureto near the melting temperature (melting point). The crystals of thesemiconductor film grow gradually by repeating melting andsolidification. In other words, regarding the crystal growth in thesemiconductor film, it is considered that the crystal grains generatedin the first irradiation are connected to each other and become largerthrough the second and subsequent irradiations. However, with the laserprocessing apparatus according to the above comparative example, thetemperature of the semiconductor film which has been raised by oneirradiation of the laser beam needs to fall to the normal temperaturebefore next irradiation of a laser beam. Thus, the processing time forone semiconductor film becomes longer, and the throughput becomeslonger.

Other problems and novel features will be apparent from the descriptionof the present specification and the accompanying drawings.

Solution to Problem

An example aspect is a laser processing apparatus includes: a laserlight source configured to irradiate a semiconductor film with a laserbeam; a film state measuring instrument configured to measure a state ofthe semiconductor film after the semiconductor film is irradiated withthe laser beam; and a laser light adjusting mechanism configured toadjust a timing at which the semiconductor film is irradiated with anext laser beam and intensity of the laser beam according to the stateof the semiconductor film measured by the film state measuringinstrument.

Another example aspect is a laser processing method including the stepsof: measuring a state of a semiconductor film irradiated with a laserbeam by a laser light source; and adjusting a timing at which the laserlight source irradiates a semiconductor film with a next laser beam andintensity of the laser beam according to the state of the semiconductorfilm.

Advantageous Effects of Invention

According to the above example aspects, it is possible to provide alaser processing apparatus and a laser processing method that caneffectively prevent a processing time for one semiconductor film fromincreasing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram for explaining a configuration of a laser processingapparatus according to a first embodiment;

FIG. 2 is a schematic diagram showing a laser beam generated by a laserbeam source of the laser processing apparatus according to the firstembodiment;

FIG. 3 is a schematic diagram for explaining a laser processing methodaccording to Comparative Example 1;

FIG. 4 is a flowchart showing a laser processing method performed by thelaser processing apparatus according to the first embodiment;

FIG. 5 is a schematic diagram for explaining a laser processing methodaccording to the first embodiment;

FIG. 6 is a diagram for explaining a configuration of a laser processingapparatus according to a second embodiment;

FIG. 7 is a diagram for explaining a configuration of a laser processingapparatus according to a third embodiment;

FIG. 8 is a schematic sectional view showing an example of a laserannealing apparatus according to a fourth embodiment;

FIG. 9 is a schematic diagram showing a laser beam generated by a lightsource of the laser annealing apparatus according to the fourthembodiment;

FIG. 10 is a schematic sectional view showing an example of a laserannealing apparatus according to a fifth embodiment;

FIG. 11 is a schematic sectional view showing an example of a laserannealing apparatus according to a sixth embodiment;

FIG. 12 is a cross-sectional view for explaining an example of a methodfor manufacturing a semiconductor apparatus according to a seventhembodiment;

FIG. 13 is a cross-sectional view for explaining the example of themethod for manufacturing a semiconductor apparatus according to theseventh embodiment;

FIG. 14 is a cross-sectional view for explaining the example of themethod for manufacturing a semiconductor apparatus according to theseventh embodiment;

FIG. 15 is a cross-sectional view for explaining the example of themethod for manufacturing a semiconductor apparatus according to theseventh embodiment; and

FIG. 16 is a cross-sectional view for explaining the example of themethod for manufacturing a semiconductor apparatus according to theseventh embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, specific embodiments will be described in detail withreference to the drawings. However, the present disclosure is notlimited to the following embodiments. In addition, the followingdescription and drawings are simplified as appropriate for clarity ofdescriptions. The same elements are denoted by the same reference signsthroughout the drawings, and repeated description is omitted asnecessary.

First Embodiment Configuration of Laser Processing Apparatus Accordingto First Embodiment

First, a configuration of a laser processing apparatus according to afirst embodiment will be described with reference to FIG. 1 . FIG. 1 isa diagram for explaining a configuration of a laser processing apparatus1 according to this embodiment. The laser processing apparatus 1 is anapparatus for irradiating the semiconductor film M1 formed over asubstrate with laser beams to crystallize the semiconductor film M1.Here, the semiconductor film M1 is, for example, a crystallized Si filmof a thin film transistor (TFT) used for a screen of a liquid crystaldisplay device. In forming the semiconductor film M1, the semiconductorfilm M1 is irradiated with a laser beam composed of a line beam, and anamorphous silicon film (a-Si film) is crystallized to form a polysiliconfilm (p-Si film). As shown in FIG. 1 , the laser processing apparatus 1includes a laser light source (laser oscillator) 2, an optical systemmodule 10, and a film state measuring instrument 5.

The laser light source 2 is a laser light source that generates pulsedlaser beams by a pulse oscillation operation. The optical system module10 includes an optical system casing 11 that constitutes an outer shape,optical elements such as a partial reflection mirror 3, reflectionmirrors 6, and a homogenizer 4, and a sealing window 23. Laser beamsgenerated by the laser light source 2 are guided to the partialreflection mirror 3 of the optical system module 10. The partialreflection mirror 3 is composed of a first partial reflection mirror 3a, a second partial reflection mirror 3 b, and a third partialreflection mirror 3 c. The first partial reflection mirror 3 a, thesecond partial reflection mirror 3 b, and the third partial reflectionmirror 3 c are optical apparatuses configured to be able to change thetransmittance, i.e., to be able to transmit some of the incident laserbeams and reflect the rest. The partial reflection mirror 3 has a roleas a laser beam adjusting mechanism for adjusting the timing at whichthe semiconductor film M1 is irradiated with a next laser beam andadjusting the intensity of the laser beam according to the state of thesemiconductor film M1 measured by the film state measuring instrument 5.

A laser beam emitted from the laser light source 2 is first guided tothe first partial reflection mirror 3 a. The laser beam transmittedthrough the first partial reflection mirror 3 a is guided to thehomogenizer 4. The homogenizer 4 is composed of a plurality ofcylindrical lenses and makes the intensity distribution uniform in arectangular shape. On the other hand, the laser beam reflected by thefirst partial reflection mirror 3 a is guided to the second partialreflection mirror 3 b. A direction of the laser beam reflected by thesecond partial reflection mirror 3 b is changed by the plurality ofreflection mirrors 6, and the laser beam is guided to the homogenizer 4.On the other hand, the laser beam transmitted through the second partialreflection mirror 3 b is guided to the third partial reflection mirror 3c. A direction of the laser beam incident on the third partialreflection mirror 3 c is reflected by the third partial reflectionmirror 3 c, a direction of the laser beam is changed by the plurality ofreflection mirrors 6, and the laser beam is guided to the homogenizer 4.

There is a difference between a length of a first optical path PT1, alength of a second optical path PT2, and a length of a third opticalpath PT3. The first optical path PT1 is an optical path that guides alight beam reflected by the first partial reflection mirror 3 a to thehomogenizer 4, the second optical path PT2 is an optical path thatguides a light beam reflected by the second partial reflection mirror 3b to the homogenizer 4, and the third optical path PT3 is an opticalpath that guides a light beam reflected by the third partial reflectionmirror 3 c to the homogenizer 4. The third optical path PT3 is thelongest, and the first optical path PT1 is the shortest (third opticalpath PT3>second optical path PT2>first optical path PT1). Thus, when alaser beam is emitted once from the laser light source 2, the laser beamfirst reaches the semiconductor film M1 through the first optical pathPT1. Next, the laser beam reaches the semiconductor film M1 through thesecond optical path PT2. Lastly, the laser beam reaches thesemiconductor film M1 through the third optical path PT3. In thismanner, the time interval (irradiation interval) at which thesemiconductor film M1 is irradiated with the laser beams can be changedby making the length of the optical path variable.

Further, the intensity of the laser beam can be changed by changing thetransmittance of the partial reflection mirror 3. That is, by changingthe transmittances of the first partial reflection mirror 3 a and thesecond partial reflection mirror 3 b, the intensity of the laser beamsthrough the first optical path PT1, the second optical path PT2, and thethird optical path PT3 can be changed, respectively.

The semiconductor film M1 is disposed over a substrate stage 45. Thefilm state measuring instrument 5 is for measuring a state of thesemiconductor film M1 after the laser beam irradiation. The film statemeasuring instrument 5 detects the state of the semiconductor film M1 bymeasuring at least one of a reflectance, a transmittance, an emissivity,and a resistance value of the semiconductor film M1. FIG. 1 shows anexample in which the film state measuring instrument 5 measures thereflectance of the semiconductor film M1.

FIG. 2 is a schematic diagram showing a laser beam applied to thesemiconductor film M1. As shown in FIG. 2 , a laser beam L1 becomes aline beam after passing through the homogenizer 4. That is, a crosssection of the laser beam L1 orthogonal to an optical axis Cl is anelongated linear shape extending in one direction. For example, a crosssection of the laser beam L1 orthogonal to the optical axis reflected bythe reflection mirror 6 is a linear shape extending in the Y-axisdirection. In order to crystallize the entire surface of the a-Si filmover the semiconductor film M1, the semiconductor film M1 is moved alongthe short axis direction (X-axis direction) of the line beamintermittently at a feed pitch of 5 to 10% of the short axis width ofthe line beam in one shot of the line beam. For example, when the shortaxis width is 0.4 mm, the feed pitch is 20 to 40 μm, and the number oftimes of the a-Si film 5 a is irradiated with laser beams per locationis 10 to 20 times.

When the laser light source 2 emits a laser beam once, the semiconductorfilm M1 is irradiated with a laser beam three times at differenttimings. For example, when the laser light source 2 emits a laser beamseven times, the semiconductor film M1 is irradiated with the laserbeams 21 times at different timings. The semiconductor film M1 isirradiated with the laser beams that have passed through the opticalpaths having different lengths, in accordance with the order of therespective lengths of the optical paths. That is, the semiconductor filmM1 is irradiated firstly with the laser beam through the first opticalpath PT1 having the shortest optical path length. Then, thesemiconductor film M1 is secondly irradiated with the laser beam throughthe second optical path PT2. After that, the semiconductor film M1 isthirdly irradiated with the laser beam through the third optical pathPT3.

When a laser beam having energy density E0 is emitted from the laserlight source 2 once, the energy density of the laser beam reaching thesemiconductor film M1 first is defined as E1, the energy density of thelaser beam reaching the semiconductor film M1 second is defined as E2,and the energy density of the laser beam reaching the semiconductor filmM1 third is defined as E3. The reflectance of the first partialreflection mirror 3 a is defined as R1, the transmittance thereof isdefined as T1, the reflectance of the second partial reflection mirror 3b is defined as R2, the transmittance thereof defined as T2, and thereflectance of the third partial reflection mirror 3 c is defined as R3.Then, E1, E2, and E3 are respectively expressed by the followingformulas.

E1=T1·E0

E2=(R1·R2)·(E0)

E3=(R1·T2·R3)·(E0)

From the above formulas, a ratio r2 of the energy density E1 of thelaser beam that reaches the semiconductor film M1 first to the energydensity E2 of the laser beam that reaches the semiconductor film M1second is r2=E2/E1=R1·R2/T1. Further, a ratio r3 of the energy densityE1 of the laser beam that reaches the semiconductor film M1 first to theenergy density E3 of the laser beam that reaches the semiconductor filmM1 third is r3=E3/E1=r3=(T2·R1·R3)/T1. In this way, the ratios r1 and r2can be changed by appropriately changing R1 to R3 and T1 to T3.

Laser Processing Method According to Comparative Example 1

Next, a laser processing method according to Comparative Example 1,which has been studied by the present inventor in advance, will bedescribed.

FIG. 3 is a schematic diagram for explaining a laser processing methodaccording to Comparative Example 1. In FIG. 3 , the relationship betweenthe temperature of the semiconductor film M1 and time is shown in theupper part, and the relationship between the laser beam intensity andtime is shown in the lower part. As shown in FIG. 3 , the laserprocessing method according to Comparative Example 1 includes thefollowing steps.

-   -   (a) The semiconductor film M1 is irradiated with a first laser        beam having energy density I0 (peak value) from the laser light        source 2, and the temperature of the semiconductor film M1        (temperature of the semiconductor film M1 at the laser beam        irradiation position) is raised to a temperature T3 higher than        or equal to a melting point T1.    -   (b) The semiconductor film M1 is irradiated with a second laser        beam having energy density I0 after the temperature of the        semiconductor film M1 is lowered to near a normal temperature        T0.    -   (c) From the irradiation of the semiconductor film M1 with the        second laser beam onward, the same processing as that of (b) is        repeated until the number of times of laser beam irradiation        becomes n. That is, after irradiating the semiconductor film M1        with the k-th (3≤k≤n−1) laser beam, a wait is made until the        temperature of the semiconductor film M1 is lowered to near the        normal temperature T0 in order to irradiate the semiconductor        film M1 with the k-th+1 laser beam having the energy density I0.

The energy density I0 of the laser beam is the optimum energy density(OED) [mJ/cm2] when the temperature of the semiconductor film M1 isabout the normal temperature T0 (about 30° C.). The crystalline qualityof p-Si greatly depends on the energy density of the irradiated laserbeam, and the energy density does not become satisfactory if it is toolow or too high. When the energy density of the laser beam applied tothe semiconductor film M1 is 10 which is the optimum energy density atthe normal temperature T0, good crystalline quality cannot be obtainedwhen the temperature of the semiconductor film M1 is 100° C. or higher.Here, the good crystalline quality means that the grain size is largeand the growth direction is uniform in the semiconductor film M1. Thus,as described above, when the energy density in each irradiation is madeequal at I0, after the semiconductor film M1 is irradiated with a laserbeam once, it waited until the temperature of the semiconductor film M1is lowered to near the normal temperature T0 to irradiate thesemiconductor film M1 with the next laser beam. That is, since theenergy density I0 is OED when the temperature of the semiconductor filmM1 is the normal temperature, in order to make the energy density ineach irradiation constant at I0, it is necessary to make the temperatureof the semiconductor film M1 before the laser beam irradiation close tothe normal temperature.

A pulse width Ts (oscillation time of one laser beam) of a laser beam iscommonly several ns to several tens of ns, and the oscillation frequencyis several hundred Hz or less. On the other hand, a waiting time Tdrequired for the temperature raised by the irradiation to fall to thenormal temperature T0 after the irradiation with a laser beam once isseveral ms, which is relatively long. Thus, in the laser processingmethod according to Comparative Example 1, the waiting time after theirradiation with a laser beam until the irradiation with the next laserbeam is long. As a result, the processing time per one semiconductorfilm is increased, and the throughput is increased.

It is known that a semiconductor film M1 having a large particle sizeand a uniform growth direction can be obtained by irradiating thesemiconductor film M1 with a laser beam a plurality of times (e.g., 20times.) and repeating a phase change of melting and solidification inthe semiconductor film M1. Here, a freezing point T2, which is thetemperature at which the melted semiconductor film M1 is solidified, isa temperature close to the melting point T1, which is the temperature atwhich the semiconductor film M1 is melted (freezing point T2 is slightlylower than melting point T1 due to the supercooling phenomenon).

For example, when the temperature of the freezing point T2 of thesemiconductor film M1 is about 800° C., when the semiconductor film M1is irradiated with a laser beam, the temperature of the semiconductorfilm M1 rises to about 1400° C. As described above, in the laserprocessing method according to Comparative Example 1, a wait is madeuntil the temperature of the semiconductor film M1 falls to about thenormal temperature T0. Thus, since the solidification temperature of thesemiconductor film M1 is about 800° C., the amount of energy releasedwhile the temperature of the semiconductor film M1 falls from 800° C. to30° C. is wasted.

Laser Processing Method Performed by Laser Processing ApparatusAccording to First Embodiment

Next, a laser processing method performed by the laser processingapparatus 1 according to the first embodiment will be described. In thelaser processing method performed by the laser processing apparatusaccording to this embodiment, the state of the semiconductor film M1 ismeasured, and the timing at which the next laser beam is applied and theenergy density of the laser beam to be irradiated are adjusted based ona result of the measurement. The state of the semiconductor film M1 isdetected by measuring at least one of a reflectance, a transmittance, anemissivity, and a resistance value of the semiconductor film M1.

FIG. 4 is a flowchart showing the laser processing method performed bythe laser processing apparatus 1 according to the first embodiment. Asshown in FIG. 4 , first, the semiconductor film M1 is irradiated withthe first laser beam having the energy density I0 (first energyintensity), and the temperature of the semiconductor film M1 is raisedto the temperature T3 higher than or equal to the melting point T1 (StepS1). At this time, the semiconductor film M1 is in an amorphous state.Next, the state of the semiconductor film M1 is measured by the filmstate measuring instrument 5 to detect the temperature of thesemiconductor film M1 (Step S2).

Following Step S2, after the detected temperature of the semiconductorfilm M1 falls to a temperature T4 lower than or equal to the freezingpoint T2, the semiconductor film M1 is irradiated with the second laserbeam having the energy density I (second energy intensity) smaller thanthe energy density I0 (Step S3). Next, it is determined whether thenumber of times of laser beam irradiation has reached a predeterminednumber (Step S4). In Step S4, when the number of times of laser beamirradiation reaches the predetermined number (YES), the process isended. In Step S3, when the number of times of laser beam irradiationhas not reached the predetermined number (NO), the process returns toStep S2. When the number of times of laser beam irradiation has reachedthe predetermined number (YES), the process is ended. When the processis ended, the semiconductor film M1 becomes a polycrystalline state.

The energy density I0 in Step S1 and the energy density I in Step S2 areset in advance by a preliminary evaluation or the like. A specificmethod for setting the energy densities I0 and I will be describedlater.

FIG. 5 is a schematic diagram for explaining the laser processing methodaccording to the first embodiment. In FIG. 5 , the relationship betweenthe temperature of the semiconductor film M1 and time is shown in theupper part, and the relationship between the laser light intensity andtime is shown in the lower part.

The temperature T4 of the semiconductor film M1 is a temperature lowerthan or equal to the freezing point T2 and sufficiently higher than thenormal temperature T0. More specifically, the temperature T4 of thesemiconductor film M1 is 100° C. or higher and the freezing point T2 orlower. When the temperature of the semiconductor film M1 is thetemperature T4 of 100° C. or higher, which is much higher than thenormal temperature, in order to improve the crystalline quality of thesemiconductor film M1 after the laser beam irradiation, it is necessaryto reduce the energy density of the laser beam to be applied in such away that it becomes smaller than I0 which is the optimum energy densityat the normal temperature T0. That is, from the second laser beamirradiation onward, it is necessary to set the energy density of thelaser beam to be applied to the optimum energy density I at thetemperature T4.

The temperature of the semiconductor film M1 when the laser beam isapplied from the second laser beam irradiation onward may not be thesame every time as long as the temperature is 100° C. or higher and thefreezing point T2 or lower. However, when the energy density forapplying the laser beam is changed every time, the energy density of thelaser beam to be applied needs to be the optimum energy density at thetemperature of the semiconductor film M1 in each laser beam irradiation.Thus, it is simple to make a third laser beam applied after the secondlaser beam have third energy intensity, which is the same energyintensity as the second energy intensity (energy density I). Afterirradiation with a third laser beam having third energy intensity, thesemiconductor film M1 becomes a polycrystalline state. It is preferableto set the temperature T4 as close to the freezing point T2 as possiblein terms of shortening the waiting time and energy saving. For example,when the freezing point T2 of the semiconductor film M1 is about 800°C., the semiconductor film M1 is irradiated with a laser beam, and thenthe next laser beam is applied when the temperature of the semiconductorfilm M1 falls to about 790° C., which is the temperature T3 lower thanor equal to the freezing point T2.

There is a correlation between the temperature and reflectance of thesemiconductor film M1 in a melted state. Thus, the timing at which thesemiconductor film M1 starts melting and the timing at which it issolidified can be detected by measuring the reflectance of thesemiconductor film M1. That is, the reflectance when the temperature ofthe semiconductor film M1 is the temperature T3 is Rt3, the reflectancewhen the temperature of the semiconductor film M1 is the melting pointT1 is Rt1, and the reflectance when the temperature of the semiconductorfilm M1 is the freezing point T2 is Rt2. Since the melting point T1 andthe freezing point T2 are substantially equal, the reflectance Rt1 andthe reflectance Rt2 are substantially equal.

Like the relationship between the temperature and the reflectance of thesemiconductor film M1, there is a correlation between the temperatureand the emissivity of the semiconductor film M1 in a melted state. Thus,the timing at which the semiconductor film M1 starts melting and thetiming at which it is solidified may be detected by measuring theemissivity of the semiconductor film M1. Furthermore, there is acorrelation between the temperature and the transmittance of thesemiconductor film M1 in a melted state. Thus, the timing at which thesemiconductor film M1 starts melting and the timing at which it issolidified may be detected by measuring the transmittance of thesemiconductor film M1.

The timing of irradiating the semiconductor film M1 with a laser beam iswhen the film state measuring instrument detects that the temperature ofthe semiconductor film M1 has fallen to a predetermined temperature of100° C. or higher and the melting point or lower. A difference betweenthe irradiation timing of the first laser beam and the irradiationtiming of the second laser beam is defined as Δt1. A difference betweenthe irradiation timing of the first laser beam and the timing when thereflectance becomes R2 after the irradiation of the first laser beam isdefined as Δt1 r. The irradiation timing of the second laser beam is setso that Δt1 becomes longer than Δt1 r (Δt1>Δt1 r). For example, thedifference Δt1 opt between Δt1 and Δt1 r is set to 50 ns. Similarly, thedifference between the irradiation timing of the k-th (2≤k≤n−1) laserbeam and the irradiation timing of the k+1th laser beam is defined asΔtk, and the difference between the irradiation timing of the k-th laserbeam and the timing at which the reflectance becomes R2 after theirradiation of the k+1th laser beam is defined as Δtkr. The irradiationtiming of the k+1th laser beam is set so that Δtk becomes longer thanΔtkr (Δtk>Δtkr). For example, the difference Δtkopt between Δt1 and Δt1r is set to 50 ns. Note that all values of Δtkopt, including Δt1 opt,may be the same or different.

A specific method for setting the energy densities I0 and I will bedescribed with reference to FIG. 5 .

First, the semiconductor film M1 before crystallization is irradiatedwith a laser beam having certain energy density by the laser lightsource 2 a predetermined number of times, and the semiconductor film M1after crystallization is observed by a microscope or the like toevaluate the crystalline quality.

By irradiating the semiconductor film M1 after crystallization withlaser beams having different energy densities by the laser light source2, the energy density that has achieved good crystalline quality amongthe different energy densities applied from the laser light source 2 isset to be the optimum energy density I0.

Next, the semiconductor film M1 before crystallization is irradiatedwith a laser beam having the set energy density I0 once, and thenirradiated with a laser beam having certain energy density smaller thanthe energy density I0 a predetermined number of times, and thesemiconductor film M1 after crystallization is observed by a microscopeor the like to evaluate the crystalline quality. By irradiating thesemiconductor film M1 after crystallization with laser beams havingdifferent energy densities by the laser light source 2, the energydensity that has achieved good crystalline quality among the differentenergy densities applied from the laser light source 2 is set to be theoptimum energy density I.

Next, the effect of the laser processing apparatus 1 according to thisembodiment will be described.

In the laser processing method performed by the laser processingapparatus 1 according to the first embodiment, after a laser beam isapplied once, the next laser beam is applied when the temperatureincreased by the irradiation becomes the freezing point T2 or lower. Bydoing so, in a case where a wait is made until the temperature of thesemiconductor film M1, which has been raised by the irradiation afterirradiation of a laser beam once, falls to about the normal temperature,the waiting time until the next laser beam is applied after a laser beamis applied can be shortened. Then, the processing time per onesemiconductor film M1 is shortened and the throughput can be shortened.

Further, the energy density of the laser beam to be applied can be madesmaller than the energy density of the laser beam to be applied for thefirst time from the second laser beam irradiation onward. This improvesthe energy saving performance.

Second Embodiment Configuration of Laser Processing Apparatus Accordingto Second Embodiment

FIG. 6 is a diagram for explaining a configuration of a laser processingapparatus 101 according to this embodiment. As shown in FIG. 6 , thelaser processing apparatus 101 further includes an attenuator 7 forattenuating a laser beam and adjusting the energy to predeterminedenergy density in addition to the components of the above-describedlaser processing apparatus 1 according to the first embodiment shown inFIG. 1 . That is, an optical system module 110 includes the attenuator 7as an optical element in addition to the partial reflection mirror 3,the reflection mirror 6, and the homogenizer 4. The attenuator 7 isprovided over the optical path between the solid-state laser 2 and thesemiconductor film M1. That is, the attenuator 7 is disposed over eachoptical path (first optical path, second optical path, and third opticalpath) leading from the first partial reflection mirror 3 a, the secondpartial reflection mirror 3 b, and the third partial reflection mirror 3c to the homogenizer 4. The attenuator 7 together with the partialreflection mirror 3 perform part of a role of a laser beam adjustingmechanism. That is, the attenuator 7 and the partial reflection mirror 3adjust the timing at which the semiconductor film M1 is irradiated witha next laser beam and adjust the intensity of this laser beam accordingto the state of the semiconductor film M1 measured by the film statemeasuring instrument 5.

Like the above-described laser processing apparatus 1 according to thefirst embodiment, in the laser processing apparatus 101 according tothis embodiment, when a laser beam is emitted once from the laser lightsource 2, the semiconductor film M1 is irradiated with laser beams threetimes at different timings. For example, when the laser light source 2emits a laser beam seven times, the semiconductor film M1 is irradiatedwith the laser beams 21 times at different timings. As described above,the semiconductor film M1 is firstly irradiated with the laser beamthrough the first optical path PT1 having the shortest optical pathlength, and then secondly irradiated with the laser beam through thesecond optical path PT2, and then thirdly irradiated with the laser beamthrough the third optical path PT3 having the longest optical pathlength.

Here, when a laser beam having energy density E0 is emitted once fromthe laser light source 2, the energy density of the laser beam thatreaches the semiconductor film M1 first is defined as E1, the energydensity of the laser beam that reaches the semiconductor film M1 secondis defined as E2, and the energy density of the laser beam that reachesthe semiconductor film M1 third is defined as E3. The reflectance of thefirst partial reflection mirror 3 a is defined as R1, the transmittanceof the first partial reflection mirror 3 a is defined as T1, thereflectance of the second partial reflection mirror 3 b is defined asR2, the transmittance of the second partial reflection mirror 3 b isdefined as T2, and the reflectance of the third partial reflectionmirror 3 c is defined as R3. An attenuation factor of an attenuator 7 ais defined as Ta0, an attenuation factor of an attenuator 7 b is definedas Ta1, an attenuation factor of an attenuator 7 c is defined as Ta2,and an attenuation factor of an attenuator 7 d is defined as Ta3. Then,E1, E2, and E3 are respectively expressed by the following formulas.

E1=(T1)·Ta1·(E0)·Ta0

E2=(R1·R2)·Ta2·(E0)·Ta0

E3=(R1·T2·R3)·Ta3·(E0)·Ta0

From the above formulas, a ratio r2 of the energy density E2 of thelaser beam that reaches the semiconductor film M1 second to the energydensity E1 of the laser beam of the laser beam that reaches thesemiconductor film M1 first is r2=E2/E1=(R1·R2/T1)·Ta2/Ta1. Further, aratio r3 of the energy density E3 of the laser beam that reaches thesemiconductor film M1 third to the energy density E1 of the laser beamof the laser beam that reaches the semiconductor film M1 first isr3=E3/E1=(R1·T2·R3/T1)·Ta3/Ta1. Thus, the ratios r1 and r2 can bechanged by appropriately changing R1 to R3 and T1 to T3.

In the laser processing apparatus 1 according to the first embodiment,the intensity of the laser beam is adjusted only by changing thetransmittance of the partial reflection mirror 3. On the other hand, inthe laser processing apparatus 101 according to this embodiment, theintensity of the laser beam is finely adjusted by the attenuators 7disposed over the first optical path, the second optical path, and thethird optical path in addition to changing the transmittance of thepartial reflection mirror 3. By doing so, it is possible to adjust theintensity of a laser beam more accurately.

The laser processing method performed by the laser processing apparatus101 according to this embodiment is the same as the laser processingmethod performed by the laser processing apparatus 1 according to thefirst embodiment except that intensity of a laser beam is finelyadjusted by the attenuator 7. Hence, the description of the laserprocessing method performed by the laser processing apparatus 101according to this embodiment is omitted.

Third Embodiment Configuration of Laser Processing Apparatus Accordingto Third Embodiment

FIG. 7 shows a configuration example of the laser processing apparatus201 according to this embodiment. In the above-described laserprocessing apparatus 1 according to the first embodiment shown in FIG. 1, there is a single laser light source 2, whereas as shown in FIG. 7 ,the laser processing apparatus 201 according to this embodiment includesa plurality of laser light sources 2 (laser light sources 2 a, 2 b, and2 c). Further, the laser processing apparatus 201 according to thisembodiment further includes a pulse generator 8 for applying laser beamsfrom the plurality of laser light sources 2 a, 2 b, and 2 c with a timedifference therebetween. The pulse generator 8 perform part of a role ofa laser beam adjusting mechanism.

In the laser processing apparatus 201 according to this embodiment, thelaser beam emission timing of each of the laser light sources 2 a, 2 b,and 2 c is adjusted by the pulse generator 8 to thereby adjust anirradiation interval between a time when a laser beam is applied and atime when a laser beam is applied next. Further, the laser processingapparatus 201 according to this embodiment further includes, in anoptical system module 210, attenuators 7 for attenuating a laser beamand adjusting the energy to predetermined energy density in addition tooptical elements such as the reflection mirror 6 and the homogenizer 4.The attenuators 7 are provided in respective optical paths from thelaser light sources 2 a, 2 b, and 2 c to the semiconductor film M1. Theattenuator 7 together with the pulse generator 8 has a part of the roleof the laser light adjusting mechanism. That is, the attenuator 7 andthe pulse generator 8 adjust the timing at which the semiconductor filmM1 is irradiated with a next laser beam and adjust the intensity of thislaser beam according to the state of the semiconductor film M1 measuredby the film state measuring instrument 5.

When there is only one laser light source, like in the above-describedlaser processing apparatus 1 according to the first embodiment, a laserbeam emitted from the laser light source needs to be divided by anoptical system such as the partial reflection mirror 3 so that thedivided laser beams pass through plurality of optical paths havingdifferent lengths to be applied to the semiconductor film M1. On theother hand, in the laser processing apparatus 201 according to thisembodiment, the configuration of the optical system can be simpler, andthus the space required for disposing the optical system can be reduced,thereby reducing the apparatus size.

The laser processing method performed by the laser processing apparatus201 according to this embodiment is the same as the laser processingmethod performed by the laser processing apparatus 1 according to thefirst embodiment except that the pulse generator 8 creates a timedifference between the timing at which the plurality of laser lightsources 2 a, 2 b, and 2 c apply laser beams.

Fourth Embodiment Configuration of Laser Annealing Apparatus Accordingto Fourth Embodiment

A laser annealing apparatus as another laser processing apparatusaccording to the fourth embodiment will be described. The laserannealing apparatus according to this embodiment performs processing forirradiating a semiconductor film formed over a substrate with a laserbeam to crystallize the semiconductor film. When laser annealing isperformed using, for example, an excimer laser as a laser beam, thelaser annealing apparatus is used as an Excimer Laser Anneal (ELA)apparatus.

FIG. 8 shows a schematic sectional view showing an example of the laserannealing apparatus according to the fourth embodiment. As shown in FIG.8 , the laser annealing apparatus 301 includes a laser light source 2,an optical system module 20, a sealing unit 30, and a processing chamber40. The processing chamber 40 is provided, for example, over ahorizontal base. The sealing unit 30 is provided above the processingchamber 40, and the optical system module 20 is provided above thesealing unit 30. The optical system module 20 is provided at a positionwhere the optical system module 20 can receive a laser beam L emittedfrom the laser light source 2.

Here, XYZ orthogonal coordinate axes are introduced in order to describethe laser annealing apparatus 301. The direction orthogonal to the uppersurface of the base 48 is defined as a Z-axis direction, an upperdirection of the Z-axis direction is defined as a +Z-axis direction, anda lower direction of the Z-axis direction is defined as a −Z-axisdirection. The direction connecting the laser light source 2 to theoptical system module 20 is defined as an X-axis direction, a directionfrom the laser light source 2 toward the optical system module 20 isdefined as a +X-axis direction, and a direction opposite to the +X-axisdirection is defined as a −X-axis direction. A direction orthogonal tothe X-axis direction and the Z-axis direction is defined as a Y-axisdirection, one direction of the Y-axis direction is defined as a +Y-axisdirection, and a direction opposite to the +Y-axis direction is definedas a −Y-axis direction.

As shown in FIG. 8 , the laser light source 2 is a laser light sourcethat emits the laser beam L10. The laser light source 2 is, for example,an excimer laser light source and emits the laser beam L10 of an excimerlaser having a center wavelength of 308 nm. The laser light source 2emits the laser beam L10 toward the optical system module 20. The laserbeam L10 travels, for example, in the +X-axis direction and enters theoptical system module 20.

As shown in FIG. 8 , the optical system module 20 includes an opticalsystem casing 21 that constitutes an outer shape, optical elements suchas a reflection mirror 6 and a lens 72, and a sealing window 23. Theoptical system casing 21 is a box-shaped member made of a material suchas aluminum. Each optical element of the optical system module 20 isheld inside the optical system casing 21 by a holder or the like. Withsuch optical elements, the optical system module 20 adjusts theirradiation direction, the light amount, and the like of the laser beamL10 emitted from the laser light source 2.

The configuration of the optical system module 10 of the laserprocessing apparatus 1 according to the first embodiment is applied as aconfiguration of the optical system module 20. The configuration of theabove-described optical system module 110 of the laser processingapparatus 101 according to the second embodiment or the configuration ofthe laser processing apparatus 201 of the optical system module 210according to the third embodiment may be applied as the configuration ofthe optical module 20.

The sealing window 23 is provided over a part of the optical systemcasing 21, for example, over a lower surface of the optical systemcasing 21. After the laser beam L10 is adjusted by the optical systemmodule 20, the laser beam L10 is emitted from the sealing window 23toward the sealing unit 30. In this way, the optical system module 20irradiates the semiconductor film M1 with the laser beam L10.

As shown in FIG. 9 , the laser beam L10 has a line beam shape in theoptical system module 20. That is, the cross section of the laser beamL10 orthogonal to an optical axis C10 is an elongated linear shapeextending in one direction. For example, a cross section of the laserbeam L10 orthogonal to the optical axis of the laser beam L10 reflectedby the reflection mirror 6 is a linear shape extending in the Y-axisdirection.

As shown in FIG. 8 , the sealing unit 30 includes a sealing casing 31, areflected light receiving member 61, a sealing window 33, a gas inlet34, and a gas outlet 35.

The sealing casing 31 is a box-shaped member with a hollow inside. Eachof the gas inlet 34 and the gas outlet 35 is provided over apredetermined side surface of the sealing casing 31. The gas inlet 34and the gas outlet 35 are provided, for example, over side surfaces ofthe sealing casing 31 opposite to each other. For example, the gasoutlet 35 is provided above the gas inlet 34. A gas 37, for example, aninert gas such as nitrogen is introduced from the gas inlet 34. The gas37 introduced inside the sealing casing 31 from the gas inlet 34 isdischarged from the gas outlet 35. It is desirable that the gas 37 becontinuously supplied inside the sealing casing 31. Further, it isdesirable that the gas 37 be continuously discharged to the outside ofthe sealing casing 31. A flow rate of the gas 37 is controlled to apredetermined flow rate so that the inside of the sealing casing 31 isconstantly ventilated.

The reflected light receiving member 61 is disposed inside the sealingcasing 31. For example, the reflected light receiving member 61 isdisposed outside the optical system module 20 in such a way that thereflected light receiving member 61 is spaced from the optical systemmodule 20. The reflected light receiving member 61 is, for example, aplate-shaped member. The reflected light receiving member 61 is disposedwith a plate surface facing the Z-axis direction. The reflected lightreceiving member 61 is disposed in such a way that it can receive areflected beam R1 of the laser beam L10 reflected to the semiconductorfilm M1. For example, the reflected light receiving member 61 isdisposed over the optical path of the reflected beam R1 in considerationof an incident angle of the laser beam L10 and a reflection angle of thereflected beam R1. Note that the reflected light receiving member 61 maybe attached to the optical system module 20 with a heat insulatingmaterial 62 and a space therebetween. By doing so, heat insulationbetween the reflected light receiving member 61 and the optical systemmodule 20 can be maintained.

The sealing window 33 is provided over a part of the sealing casing 31,for example, over a lower surface of the sealing casing 31. The laserbeam L10 emitted from the sealing window 23 of the optical system module20 is emitted from the sealing window 33 of the sealing unit 30 towardthe processing chamber 40.

The processing chamber 40 includes a gas box 41, a substrate stage 45, asubstrate base 46, and a scanning apparatus 47. For example, in theprocessing chamber 40, the semiconductor film M1 disposed over thesubstrate stage 45 is irradiated with the laser beam L10 and thensubject to laser annealing processing for crystallizing thesemiconductor film M1. The substrate stage 45 may be a float type stage,i.e., a stage that transports the substrate over which the semiconductorfilm M1 to be irradiated is floated.

The gas box 41 is a box-shaped member with a hollow inside. The gas box41 is disposed above the substrate stage 45 and below the sealing window33 in the sealing unit 30. An introduction window 42 is provided over anupper surface of the gas box 41. The introduction window 42 is disposedto face the sealing window 33. An irradiation window 43 is provided overa lower surface of the gas box 41. The irradiation window 43 is disposedto face the semiconductor film M1.

A gas inlet 44 is provided over a predetermined side surface of the gasbox 41. A predetermined gas 37, for example, an inert gas such asnitrogen is supplied to the gas box 41 from the gas inlet 44. After theinside of the gas box 41 is filled with the gas 37 supplied to the gasbox 41, the gas 37 is discharged from the irradiation window 43.

The laser beam L10 incident over the gas box 41 is emitted from theirradiation window 43 and applied to the semiconductor film M1. Thereflected light receiving member 61 is disposed in such a way that itcan receive the reflected beam R10 reflected by the semiconductor filmM1 of the laser beam L10 applied to the semiconductor film M1.

The semiconductor film M1 is disposed over the substrate stage 45. Thesubstrate stage 45 is disposed over the scanning apparatus 47 with, forexample, a substrate base 46 interposed therebetween. The substratestage 45 can be moved by the scanning apparatus 47 in the X-axisdirection, the Y-axis direction, and the Z-axis direction. When thelaser annealing processing is performed, the substrate stage 45 istransported by the scanning of the scanning apparatus 47, for example,in a transport direction 49 in the −X-axis direction.

Further, the laser annealing apparatus 301 according to this embodimentincludes a reflectance measuring system as a film state measuringinstrument. The reflectance measuring system includes a measuring lightsource 71, a lens 72, a reflected light detector 73, a digitizer 74, aninformation processing apparatus 75, etc.

For example, a He—Ne laser is used as the measuring light source 71. Ameasuring laser beam L20 having an incident angle α with a normal lineZn of a plane of the semiconductor film M1 is made incident over thesurface of the semiconductor film M1 after the semiconductor film M1 isirradiated with the laser beam L10, and a reflected beam R20 from thesurface of the semiconductor film M1 is detected by a reflected lightdetector 73. The reflected beam R20 is a reflected beam in a directionforming a reflection angle α with a normal line zn, a direction of thelaser beam is changed by the reflection mirror 6, and the reflected beamR20 enters the reflected light detector 73 via the lens 72. The opticalelements, such as the reflection mirror 6 and the lens 72, which guidethe reflected beam R20 to the reflected light detector 73, are disposedinside the sealing unit 30. The reflected light detector 73 is alsodisposed inside the sealing unit 30.

The reflected beam R20 detected by the reflected light detector 73 isconverted into an electric signal, and the intensity of the reflectedbeam is measured by the information processing apparatus 75 such as thedigitizer 74 and a personal computer (PC). The information processingapparatus 75 determines the state of the semiconductor film M1 based onthe intensity of the reflected beam R20. That is, the reflectance of thesemiconductor film M1 in the melted state is greater than thereflectance of the semiconductor film M1 in the solid state.

In the laser annealing apparatus 301 according to this embodiment, aftera laser beam is applied once, the next laser beam is applied when thetemperature increased by the irradiation becomes the freezing point T2or lower. By doing so, when a wait is made until the temperature of thesemiconductor film M1, which has been raised by the irradiation afterirradiation of a laser beam once, falls to about the normal temperature,the waiting time until the next laser beam is applied after a laser beamis applied can be shortened. Then, the processing time per onesemiconductor film M1 is shortened and the throughput can be shortened.The flow of the laser processing method performed by the laser annealingapparatus 301 is the same as that of the laser processing methodperformed by the laser processing apparatus 1 according to the firstembodiment (see FIG. 4 ), and thus description thereof is omitted.

As described above, there is a correlation between the temperature andthe reflectance of the melted semiconductor film M1 in a melted state.Thus, the timing at which the semiconductor film M1 starts melting andthe timing at which it is solidified can be detected by measuring thereflectance of the semiconductor film M1 by the reflectance measuringsystem as the film state measuring instrument.

Fifth Embodiment Configuration of Laser Annealing Apparatus According toFifth Embodiment

A laser annealing apparatus as another laser processing apparatusaccording to a fifth embodiment will be described. FIG. 10 is aschematic sectional view showing an example of a laser annealingapparatus according to the fifth embodiment. A configuration of a laserannealing apparatus 401 according to this embodiment is basically thesame as that of the laser annealing apparatus 301 according to thefourth embodiment. The laser annealing apparatus 301 according to thefourth embodiment includes a reflectance measuring system as a filmstate measuring instrument, while the laser annealing apparatus 401according to this embodiment includes an emissivity measuring system asa film state measuring instrument.

As shown in FIG. 10 , the emissivity measuring system of the laserannealing apparatus 401 includes a lens 72, an emitted light detector173, a digitizer 74, an information processing apparatus 75, etc. Anemitted beam Ra110, which is a part of the emitted beam emitted byheating an area over the surface of the semiconductor film M1 irradiatedwith the laser beam L10, enters the emitted light detector 173. Opticalelements, such as the reflection mirror 6 and the lens 72, which guidethe emitted beam Ra110 to the emitted light detector 173, are disposedinside the sealing unit 30. The emitted light detector 173 is alsodisposed inside the sealing unit 30. The emitted beam Ra110 detected bythe emitted light detector 173 is converted into an electric signal, andthe intensity of the emitted beam is measured by the digitizer 74 or theinformation processing apparatus 75. The information processingapparatus 75 determines the state of the semiconductor film M1 based onthe intensity of the emitted beam Ra110.

In the laser annealing apparatus 401 according to this embodiment, aftera laser beam is applied once, the next laser beam is applied when thetemperature increased by the irradiation becomes the freezing point T2or lower. By doing so, when a wait is made until the temperature of thesemiconductor film M1, which has been raised by the irradiation afterirradiation of a laser beam once, falls to about the normal temperature,the waiting time until the next laser beam is applied after a laser beamis applied can be shortened. Then, the processing time per onesemiconductor film M1 is shortened and the throughput can be shortened.The flow of the laser processing method performed by the laser annealingapparatus 401 is the same as that of the laser processing methodperformed by the laser processing apparatus 1 according to the firstembodiment (see FIG. 4 ), and thus description thereof is omitted.

As described above, there is a correlation between the temperature andthe emissivity of the melted semiconductor film M1 in a melted state.Thus, the timing at which the semiconductor film M1 starts melting andthe timing at which it is solidified can be detected by measuring thereflectance of the semiconductor film M1 by the emissivity measuringsystem as the film state measuring instrument.

Sixth Embodiment Configuration of Laser Annealing Apparatus According toSixth Embodiment

A laser annealing apparatus as another laser processing apparatusaccording to a sixth embodiment will be described. FIG. 11 is aschematic sectional view showing an example of a laser annealingapparatus according to the sixth embodiment. A laser annealing apparatus501 according to this embodiment includes a transmittance measuringsystem as the film state measuring instrument. This is a differencebetween the laser annealing apparatus according to the sixth embodimentand the laser annealing apparatus 301 according to the fourth embodimentincluding the reflectance measuring system as the film state measuringinstrument.

As shown in FIG. 11 , the transmittance measuring system of the laserannealing apparatus 501 includes a measuring light source 71, a lens 72,a transmitted light detector 273, a digitizer 74, an informationprocessing apparatus 75, etc. A measuring laser beam L20 is madeincident over the surface of a semiconductor film M1 after thesemiconductor film M1 is irradiated with a laser beam L10, and atransmitted beam Tr10 transmitted through the semiconductor film M1 isdetected by the transmitted light detector 273. A groove 145 a fortransmitting the transmitted beam Tr10 downward is formed in thesubstrate stage 145 over which the semiconductor film M1 is mounted. Thesubstrate stage 145 may be a float type stage, i.e., a stage thattransports the substrate over which the semiconductor film M1 to beirradiated is floated.

A direction of the transmitted beam Tr10 is changed by the reflectionmirror 6 and enters the transmitted light detector 273 via the lens 72.Optical elements such as the reflection mirror 6 and the lens 72 forguiding the transmitted beam Tr10 to the transmitted light detector 273are disposed below the substrate stage 145. The transmitted lightdetector 273 is also disposed below the substrate stage 145.

The transmitted beam Tr10 detected by the transmitted light detector 273is converted into an electric signal, and the intensity of the emittedlight is measured by the digitizer 74 or the information processingapparatus 75 such as a personal computer (PC). The informationprocessing apparatus 75 determines the state of the semiconductor filmM1 based on the intensity of the transmitted beam Tr10.

In the laser annealing apparatus 501 according to this embodiment, aftera laser beam is applied once, the next laser beam is applied when thetemperature increased by the irradiation becomes the freezing point T2or lower. By doing so, when a wait is made until the temperature of thesemiconductor film M1, which has been raised by the irradiation afterirradiation of a laser beam once, falls to about the normal temperature,the waiting time until the next laser beam is applied after a laser beamis applied can be shortened. Then, the processing time per onesemiconductor film M1 is shortened and the throughput can be shortened.The flow of the laser processing method performed by the laser annealingapparatus 501 is the same as that of the laser processing methodperformed by the laser processing apparatus 1 according to the firstembodiment (see FIG. 4 ), and thus description thereof is omitted.

As described above, there is a correlation between the temperature andthe transmittance of the melted semiconductor film M1 in a melted state.Thus, the timing at which the semiconductor film M1 starts melting andthe timing at which it is solidified can be detected by measuring thetransmittance of the semiconductor film M1 by the transmittancemeasuring system as the film state measuring instrument.

Seventh Embodiment Method for Manufacturing Semiconductor ApparatusAccording to Seventh Embodiment

Next, as a seventh embodiment, a method for manufacturing asemiconductor apparatus in the above-described laser processingapparatus will be described. In this embodiment, the laser annealingapparatus described in the fourth embodiment, fifth embodiment, or thesixth embodiment is used as the laser processing apparatus. The methodfor manufacturing a semiconductor apparatus according to this embodimentincludes a step of preparing an object to be processed including asubstrate and an amorphous semiconductor film formed over the substrateand a step of irradiating the semiconductor film with a laser beam andcrystallizing the semiconductor film. As the object to be processed, asubstrate over which an amorphous semiconductor film is formed, forexample, a glass substrate over which amorphous silicon is formed, isused. In the step of crystallizing the amorphous semiconductor film,laser annealing processing using the above-described laser annealingapparatus described in the fourth to sixth embodiment is performed.

The semiconductor apparatus includes a TFT (Thin Film Transistor). Inthis case, an amorphous silicon film is irradiated with a laser beam andthen crystallized, so that a polysilicon film is formed.

FIGS. 12 to 16 are cross-sectional views showing an example of themethod for manufacturing a semiconductor apparatus. The above-describedlaser processing apparatus according to this embodiment is suitable formanufacturing a TFT array substrate. Hereinafter, a method formanufacturing a semiconductor apparatus including a TFT will bedescribed.

First, as shown in FIG. 12 , a gate electrode 92 is formed over a glasssubstrate 91. For example, a metal thin film containing aluminum or thelike can be used as the gate electrode 92. Next, as shown in FIG. 13 , agate insulating film 93 is formed over the gate electrode 92. The gateinsulating film 93 is formed to cover the gate electrode 92. After that,as shown in FIG. 14 , an amorphous silicon film 94 is formed over thegate insulating film 93. The amorphous silicon film 94 is disposed tooverlap the gate electrode 92 with the gate insulating film 93interposed therebetween. As described above, first, a substrate overwhich an amorphous semiconductor film is formed is prepared (Step A).

The gate insulating film 93 is a silicon nitride film (SiN_(x)), asilicon oxide film (SiO₂ film), or a laminated film of these, etc.Specifically, the gate insulating film 93 and the amorphous silicon film94 are continuously formed by a CVD (Chemical Vapor Deposition) method.The glass substrate 91 with the amorphous silicon film 94 becomes thesemiconductor film M in the laser processing apparatus.

Then, as shown in FIG. 15 , the amorphous silicon film 94 is irradiatedwith a laser beam to crystallize the amorphous silicon film 94 using theabove-described laser processing apparatus, so that a polysilicon film95 is formed. For example, a first position control signal forcontrolling a disposed position of the substrate over the substratestage 45 is transmitted to a loading/unloading apparatus (not shown)that loads and unloads the substrate (Step B). Then, the substrate isdisposed by the loading/unloading apparatus at a first position over thesubstrate stage 45 determined by the first position control signal (StepC). After that, the substrate is transported over the substrate stage 45(Step D), and the substrate is irradiated with a laser beam topolycrystallize an amorphous semiconductor film (Step E). After theamorphous semiconductor film is polycrystallized, the substrate isunloaded by the loading/unloading apparatus (Step F).

When all the irradiation areas are not irradiated, a second positioncontrol signal is further transmitted to the loading/unloading apparatus(Step G), and the substrate is disposed by the loading/unloadingapparatus to a second position different from the first position overthe substrate stage 45 determined by the second position control signal(Step H). Then, the substrate is transported to a laser beam irradiationposition over the substrate stage 45 (Step I), and the substrate isirradiated with a laser beam (Step J). Then, the polysilicon film 95 inwhich silicon is crystallized is formed over the gate insulating film93.

At this time, in the above-described laser processing method performedby the laser processing apparatus according to this embodiment, after alaser beam is applied once, the next laser beam is applied when thetemperature increased by the irradiation becomes the freezing point orlower. Thus, the waiting time after the irradiation of the laser beamuntil the temperature of the semiconductor film M1, which has risen bythe irradiation, drops to about the normal temperature after theirradiation of the laser beam, can be shortened. Then, the processingtime per one semiconductor film M1 is shortened and the throughput canbe shortened.

After all the irradiation areas are irradiated and the semiconductorfilm is polycrystallized, the substrate is unloaded by theloading/unloading apparatus (Step K).

After that, as shown in FIG. 16 , an interlayer insulating film 96, asource electrode 97 a, and a drain electrode 97 b are formed over thepolysilicon film 95. The interlayer insulating film 96, the sourceelectrode 97 a, and the drain electrode 97 b can be formed by using acommon photolithography method or film forming method.

A semiconductor apparatus provided with a TFT including apolycrystalline semiconductor film can be manufactured using theabove-described method for manufacturing a semiconductor apparatus. Sucha semiconductor apparatus may be used for controlling a display. Notethat the subsequent manufacturing steps differ depending on the deviceto be eventually manufactured, and thus the description of thesubsequent manufacturing steps will be omitted.

As described above, the disclosure achieved by the inventor has beenspecifically described based on the embodiments. However, the presentdisclosure is not limited to the embodiments, and various modificationscan be made without departing from the scope of the disclosure, as amatter of course. Further, the configuration in each embodiment may beappropriately exchanged between the embodiments.

REFERENCE SIGNS LIST

-   -   1, 101, 201 LASER PROCESSING APPARATUS    -   2 LASER LIGHT SOURCE    -   3 PARTIAL REFLECTION MIRROR    -   3 a FIRST PARTIAL REFLECTION MIRROR    -   3 b SECOND PARTIAL REFLECTION MIRROR    -   3 c THIRD PARTIAL REFLECTION MIRROR    -   4 HOMOGENIZER    -   5 FILM STATE MEASURING INSTRUMENT    -   6 REFLECTION MIRROR    -   7 (7 a, 7 b, 7 c, 7 d) ATTENUATOR    -   8 PULSE GENERATOR    -   20, 110, 210 OPTICAL SYSTEM MODULE    -   11, 21 OPTICAL SYSTEM CASING    -   23 SEALING WINDOW    -   30 SEALING UNIT    -   31 SEALING CASING    -   33 SEALING WINDOW    -   34 GAS INLET    -   35 GAS OUTLET    -   37 GAS    -   40 PROCESSING CHAMBER    -   41 GAS BOX    -   42 INTRODUCTION WINDOW    -   43 IRRADIATION WINDOW    -   44 GAS INLET    -   45 SUBSTRATE STAGE    -   46 SUBSTRATE BASE    -   47 SCANNING APPARATUS    -   48 BASE    -   49 TRANSPORT DIRECTION    -   61 REFLECTED BEAM RECEIVING MEMBER    -   62 HEAT INSULATING MATERIAL    -   71 MEASURING LIGHT SOURCE    -   72 LENS    -   73 REFLECTED LIGHT DETECTOR    -   74 DIGITIZER    -   75 INFORMATION PROCESSING APPARATUS    -   145 SUBSTRATE STAGE    -   145 a GROOVE    -   173 EMITTED LIGHT DETECTOR    -   273 TRANSMITTED LIGHT DETECTOR    -   301, 401, 501 LASER ANNEALING APPARATUS    -   M1 SEMICONDUCTOR FILM

1-8. (canceled)
 9. A method for manufacturing a semiconductor apparatuscomprising the steps of: (a) irradiating a semiconductor film with afirst laser beam having first energy intensity; and (b) after the step(a), irradiating the semiconductor film with a second laser beam havingsecond energy intensity when a temperature of the semiconductor filmfalls within a range between 100° C. or higher and a freezing point orlower, the second energy intensity being smaller than the first energyintensity.
 10. The method according to claim 9, further comprising astep of: (c) after the step (b), irradiating the semiconductor film witha third laser beam having third energy intensity, the third energyintensity being the same as the second energy intensity.
 11. The methodaccording to claim 9, further comprising a step of: measuring atemperature of the semiconductor film between the step (a) and the step(b).
 12. The method according to claim 9, wherein in the step (a), thesemiconductor film becomes an amorphous state, and after the step (b),the semiconductor film becomes a polysilicon state.
 13. The methodaccording to claim 9, wherein the semiconductor film constitutes a thinfilm transistor.
 14. The method according to claim 13, wherein the thinfilm transistor is used to control a display.
 15. The method accordingto claim 9, wherein the semiconductor film is mainly composed of asilicon. 16-20. (canceled)